Heart rate turbulence

Heart rate variability (HRV), heart rate turbulence (HRT), and baroreceptor reflex sensitivity (BRS) comprise the three currently used measures of autonomic tone. Autonomic tone is implicated in the pathogenesis of VT/VF, mainly as a result of enhanced sympathetic tone and diminished parasympathetic tone (64). Thus, analysis of autonomic tone may correlate with arrhythmic events or total mortality. 

Barthel P, Schneider R, Bauer A, et al. Risk stratification after acute myocardial infarction by heart rate turbulence. Circulation 2003 108 (10) 1221-6. 

Ghuran A, Reid F, La Rovere MT, et al. Heart rate turbulence-based predictors of fatal and nonfatal cardiac arrest (the Autonomic Tone and Reflexes After Myocardial Infarction Substudy). Am J Cardiol 2002 89(2) 184-90. 

Soguero-Ruiz C, Lechuga-Suarez L, Mora-Jimenez I, Ramos-Lopez J, Barquero-Perez O, Garcia-Alberola A et al. Ontology for heart rate turbulence domain from the conceptual model of SNOMED-CT. IEEE Transactions on Biomedical Engineering, 2013 60(7) 1825-1833. 

Schmidt, G., et al.. Heart-rate turbulence after ventricular premature beats as a predictor of mortality after acute myocardial infarction. Lancet, 1999. 353(9162) p. 1390-6. 

Undoubtedly, the most promising modehng of the cardiac dynamics is associated with the study of the spatial evolution of the cardiac electrical activity. The cardiac tissue is considered to be an excitable medium whose the electrical activity is described both in time and space by reaction-diffusion partial differential equations [519]. This kind of system is able to produce spiral waves, which are the precursors of chaotic behavior. This consideration explains the transition from normal heart rate to tachycardia, which corresponds to the appearance of spiral waves, and the fohowing transition to fibrillation, which corresponds to the chaotic regime after the breaking up of the spiral waves, Figure 11.17. The transition from the spiral waves to chaos is often characterized as electrical turbulence due to its resemblance to the equivalent hydrodynamic phenomenon. 

Other noninvasive techniques to identify risk, such as baroreflex sensitivity, spectral turbulence (45 7), heart rate variability, T-wave altemans (48-51), QT interval prolongation, QT dispersion (52,53), and late potentials (by the signal averaged ECG) (54-56), have been considered in select patient populations (Table 14.2). AU have failed to live up to initial promises. 

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